It is possible to drive from Geiteyjarstrønd to Bláfjall. It's about 35 kilometers each way. This trip requires 4X4 hole pull and the higher the car the better. If you do not have a car that fits, you can request assistance from me with my 7 seater car.
From Geiteyjarstönd you drive to the south ie you turn right when you reach the main road. When you see signs with Grænavatn you turn south. Continue for about 4 or 5 kilometers until you find a way (if you can talk about a road) going east. You must then use your imagination to determine what is the road since it is forbidden to drive off the road. The road goes in a thousand turns along with beautiful lava formations. You run across sand lava and other rarities.
When entering Bláfjall you can choose to enter Selahjallagil or walk up the slope towards the top of Bláfjall.
Fantastic trip, but I recommend bringing local friends. Contact me if you need assistance.